Q. Bilingualism used to be considered a negative thing — at least in the United States. Is it still?

A. Until about the 1960s, the conventional wisdom was that bilingualism was a disadvantage. Some of this was xenophobia. Thanks to science, we now know that the opposite is true.

Q. Many immigrants choose not to teach their children their native language. Is this a good thing?

A. I’m asked about this all the time. People e-mail me and say, “I’m getting married to someone from another culture, what should we do with the children?” I always say, “You’re sitting on a potential gift.”

There are two major reasons people should pass their heritage language onto children. First, it connects children to their ancestors. The second is my research: Bilingualism is good for you. It makes brains stronger. It is brain exercise.